An apostle of the Algäu, died about 750 (655?). The history of Saint Magnus is shrouded in obscurity. The only source is an old “Vita S. Magni”, which, however, contains so many manifest anachronisms that little reliance can be placed on it. It relates that two Irish missionaries Columbanus and Gall, spent some time with Willimar, a priest at Arbon. Here Gall fell sick and was put in charge of Magnus and Theodore (Maginald and Theodo), two clerics living with Willimar, while Columbanus proceeded to Italy and founded the monastery of Bobbio. When Gall had been miraculously informed of the death of Columbanus he sent Magnus to pray at his grave in Bobbio. Magnus returned from Bobbio with the staff of Columbanus and thereafter they followed his rule. After the death of Gall, Magnus succeeded him as superior of the cell.

About this time a priest of the Diocese of Augsburg, named Tozzo, came as a pilgrim to the grave of Saint Gall and invited Magnus to accompany him to the eastern part of Algäu. Magnus proceeded to Eptaticus (Epfach), where Bishop Wichbert of Augsburg received him and entrusted him with the Christianization of Eastern Algäu. He penetrated into the wilderness, then crossed the River Lech at a place which is still known as Saint Mangstritt (footstep of Saint Magnus) and built a cell, where afterwards the monastery of Füssen was erected, and where he died.

The “Life” is said to have been written by Theodore, the companion of Magnus, and placed in the grave under the head of Saint Magnus. When in 851 Bishop Lanto transferred the relics to the newly erected church of Fussen, this “Life” is said to have been found in a scarcely legible condition, and to have been emendated and rewritten by Ermenrich, a monk of Ellwangen. It was re-edited with worthless additions in 1070 by Othloh of Saint Emmeram. A manuscript is preserved at the Monastery of Saint Gall. The chief inconsistencies in the “Life” are the following: Saint Magnus is made a disciple of Saint Gall (died 627) and at the same time he is treated as a contemporary of Wichbert, the first historically established bishop of Augsburg (died about 749). Other manifest impossibilities have induced Mabillon, Rettberg, Hanck, and others, to reject the whole “Life” as a forgery of a much later date, while Steichele, Baumann, and many others conclude that the first part of the wife”, where Magnus is made a companion of Saint Gall, is a later addition, and that the second part was written in 851 when the relics of the saint were transferred. The opinion of Steichele and Baumann is the one generally followed at present. They maintain that a monk of Ellwangen (probably not Ermenrich, as Goldast asserts without any authority) wrote the “Life” in 851, when the body of Magnus was transferred. To attach more weight to the “Life”, the story was given out that it had been written by Theodore, the companion of Magnus, and was found with the body of the saint but in a scarcely legible condition; that therefore a monk of Ellwangen was ordered to rewrite it. (This was a common custom of the early Middle Ages.) The “Life”, as it was written by the monk of Ellwallgen, is an account of the ninth-century popular tradition. When Bishop Abbot Solomon III of Constance dedicated a church in honour of Saint Magnus at the monastery of Saint Gall, he received a relic and the “Life” from the monks of Füssen. The monks of Saint Gall had a tradition of another Magnus, who was a companion of Saint Gall and lived 100 years before the Apostle of the Algau. They now wrote a new “Life”, in which they blended the tradition of the earlier Magnus with the “Life” which they had received from Füssen. This accounts for the historical discrepancies. His feast is celebrated on 6 September.